Electrostatic precipitator



Feb. 9, 1954 D. R. 'vVHlTTET ELECTROSTATIC PRECIPITAT'OR 5 Sheets-Sheet 1 Filed Sept. 15, 1952 i val- 4 L w 3 llll in A}... I! aliv It 4 am) I ,E 1 F a 4 E 3 m a. m

Feb. 9, 1954 Filed Sept. 15, 1952 D. R. WHITTET ELECTROSTATIC PRECIPITATQR 3 Sheets-Sheet 2 bl'iornej y Feb. 9, 1954 D. R. WHlTTET 2,668,599

ELECTROSTATIC PRECIPITATOR Filed Sept. 15, 1952 3 Sheets-Sheet 3 afi enfor p torn eys Patented Feb. 9, 1954 UNITED STAT ATENT OFFICE ELECTROSTATIC PRECIPITATOR company Application September 15, 1952, Serial No. 309,590

Claims priority, application Great Britain September 24, 1951 7 Claims.

In an electrostatic gas-cleaner wherein the gas is passed through an electrostatic field between electrode surfaces at different potentials the particles may be precipitated on to a collecting surface consisting of a film of liquid-e. g. waterflowing over a collector and carrying the particles away continuously, to make the precipitator self-cleaning. The film may conveniently be formed on the inside wall of a vertical tube forming a container for the precipitator. V

The liquid should form an uninterrupted film over the whole of the wall, because certain particles (in particular carbon black), on reaching a dry part of the collecting surface, tend to give up their charge and, acquiring an opposite charge by induction, may experience suflicient force in a strong field to be moved back again towards the other electrode and may thereafter be kept in oscillation between the electrodes until finally they pass out of the cleaner with the gas; particles reaching the wet surface however tend to be retained by the liquid once they have touched it. If a liquid such as water be merely poured into the vertical tube it tends to trickle down in separate streams and it is difiicult to ensure that it will spread over the whole inside wall surface without an excessive flow of incoming liquid.

This defect can be overcome by providing an internally-cylindrical vertical container tube constituting the collector with means for admitting liquid to this tube as a film, formed on and having a swirling motion around the inside cylindrical surface of the tube; this film tends to Wet the whole inside circumference of the wall of the tube adjacent the inlet. Although the swirl gradually disappears along the length of the tube it has been found that the tendency is to maintain the film around the Whole circumference of the tube throughout its length. Moreover, with an increase in liquid poured in without swirl there is a tendency for the flow to separate from the wall, whereas when the liquid is swirling, centrifugal force urges the liquid outward on to the wall of the tube. The invention consists in providing the top end of the container tube with a chambered ferrule, incorporating a liquid-receiving chamber and pierced by at least one liquid-supply hole from the chamber into the interior of the ferrule substantially tangentially to the inside surface of the ferrule.

It is desirable that the means for admitting the swirling liquid should not prevent a number of container tubes from being closely stacked together. Hence, in order to save space, when there are banks of tubes, by stacking the tubes in staggered banks as closely as possible, in tangential contact or nearly so, and admitting the liquid to chambers in elements in the somewhat triangular-shaped spaces between groups of three adjacent tubes, the invention also consists in the provision of fittings which occupy these spaces and which fit together to make up rings which form the ferrules around the tubes.

The invention is illustrated by the accompanying drawings of which:

Fig. 1 is a vertical sectional view of a bank of tubular containers for precipitators according to the invention.

Figs. 2 and 3 are a plan and an inverted plan view thereof, and

Figs. 4 to 9 are views of details of the construction according to Figs. 1, 2 and 3.

In Figs. 1 to 3 the plant consists of precipitators, each of which is enclosed in a vertical cylindrical collector and container tube 2|. A header for the top of banks of tubes 2| is built up of a number of chambered elements 22, 23 and 24, each of which forms part of a chambered ferrule for a tube. Each element 22, as shown separately in enlarged plan and inverted planv views, Figs. 4 and 5, and in further enlarged perspective in Fig. 6, is bounded by three equal concave sides 2211 which are arcs (of one sixth of a circumference) of a circle of slightly less radius than the insides of the tubes 2| and by three bevelled corners 2279. In the centre of the element (see Fig. 4) is a hole 220 extending from the top face down towards the bottom, but not right through; this hole forms the liquid-receiving chamber. Three oblique holes 22d enter chamber 220, one from each of the sides 22a, at such an angle as to be substantially tangential to the sides; these are the liquid-supply holes. In the bottom face of the element (see Fig. 5) are three equal arcuate grooves 22c, parallel to the.

three sides 22a, each groove having the same mean radius as a tube 2| and a width such that it will fit tightly on to the rim of a tube as shown in section in Fig. 1. used to clamp together three of the tubes 2 l i. e. three tubes 2! are put symmetrically close together and one element 22 is pressed on to their open ends so as to cover the gap formed between the tops of the three tubes, with the three arcuate grooves 22c fitting over parts of the rims of each of the tubes; the element then holds the three tubes together at the top. Another element 22 placed on two of these three tubes clamps them to another tube, and so on, a bank being built up as shown in Fig. 2. Six elements Thus each element 22 is 22 around each tube make up a complete ferrule with six tangential liquid-inlet holes 22d from six chambers 220. Each tube, except end tubes, is then surrounded by six other tubes in tangential contact or nearly touching. The sides of the header are made up partly of elements 22 fitting on to only two tubes and partly of elements 24 which each fit on to only one tube; the former have only two liquid supply holes 22d, the third hole being omitted or plugged. Elements 24 are of a shape modified from elements 22 by the shortening of two of the arcuate sides and they have only one supply hole 22d. Although a complete header could be made up only of elements 22 and 24, some elements 23 are shown engaging four tubes and of a shape identical with two elements 22 combined integrally together. Thus around the top of each tube 2| is a ferrule with six liquid supply holes and made up of a combination of elements 22 and 24 or 22, 23, and 24 which is equivalent to six of the elements 22.

Each of the elements has on its upper face a central hollow spigot 22f, around the chamber 22c, screw-threaded to receive a standard union on the liquid supply piping shown separately at- 25 in- Fig. 7, this being preferable to tapping the hole 22c and screwing the pipe in. To complete the header, sheet metal pieces 26 and 21, having upturned arcuate portions fittin in the grooves 22c, are inserted along the sides and at the corners. Piece 26, partly cut away to show its section, is shown separately in Fig. 8 andpiece 21 in Fig. 9.

Any convenient arrangement may be provided at the bottom of the stacks of tubes for collecting and draining-oft the water. In Figs. 1 and 3 the lower ends of tubes 2| and of gas-outlet tubes 28 projecting therein are secured to the sump 3|, the tubes 28 passing through the bottom of the sump; tubes 28 may be attached to tubes 2| by spacers 29 and to the base of the sump 3| by flanges 30. The sump is provided with drain pipes, of which some are indicated at 32.

The elements 22, 23 and 24 may conveniently be die-cast in some light alloy. The central cavity 22c will then be cored in the casting and the tangential holes 22d may also be cored instead of drilled; the arcuate grooves 22:; will probably fit the pipes 2| quite well without machining. The arcuate faces 22a of the die-castings should form together a sufficiently smooth internal ring around the top of each tube; the meeting faces of adjacent elements in a ring are the corners 221) which are preferably inclined at about 45 or more to a radius, so as to meet with an overlap. With good castings, liquid leaking through these joints and running down. the outside of the tubes should be negligible. The tapping of hole 220 or external screw-threading of spigot 22, for the connection from piping 25 need be the only machining operation on the die castings.

Each tube 2| forms the internally cylindrically container tube and collector for an electrostatic precipitator. While this could for example be of the kind according to the co-pending British Patent application No. 3386/50 it is shown for simplicity in Fig. 1 as of the common kind wherein one electrode is the wire 33 suspended between the insulators 34 which are supported in the usual manner by the narrow upper crosssupport :35 and lower cross-support 36.

In operation, air or other gas to be cleaned flows downwards through tubes 2| and 28 as indicated by the arrows A. When, by connection of wire 33 to an electric supply, the appropriate potential difference is maintained between the wire and a swirling film of earth-potential liquid running down. the inside of tube 2|, charged particles will be deposited on the liquid film and will be carried down thereby to the sump and thence away by drain pipes 32.

Liquid supplied from piping 25 to the central chamber 220 of each element divides into three streams which go tangentially into three different tubes; the six tangential jets entering each tube 2| come from six different cavities and accordingly a blockage of one supply pipe of the piping 25,. although affecting three of the tubes 2|, will stop only one sixth of the liquid supply to each of them and so should not put any one tube out of action. The liquid from each chamber 22c passes through holes 22d to emerge on to the interior surface of each ferrule tangentially and thus swirls around the interior of the ferrule and of the tube 2.1-.

I claim:

1. Precipitating plant made up of a. plurality of electrostatic precipitators in separate internally-cylindrical upright tubes constituting collectors and containers, closely stacked in stag gered banks, said tubes being substantially in. tangential contact, and means for admitting. liquid to each said tube as a. film formed on and swirling around the inside cylindrical surface of the tube which means comprise a chambered ferrule on the top end ofeach container tube pierced by at least one liquid-supply hole from, a chamber in the ferrule into the interior of the ferrule substantially tangentially to the inside. surface of the ferrule, wherein said ferrule is made up of separate elements, at least one of which is formed with arcuate portions engaging and holding together at least three mutually tangential container tubes, and with a said chamber located in the three-sided space between said three tubes.

2. Precipitating plant according to claim 1 wherein said elements are formed with arcuate grooves which receive and fit on to part of the top rim of a container tube.

3. Precipitating plant according to claim 1 wherein at least one of said elements is of substantially equilateral triangular form with three arcuate sides each'forming one sixth of a circular ferrule, and under face having three of said arcuate grooves parallel to said sides tov fit the three tangential tubes, and a top face in the centre of which is formed the said chamber, there being three of said liquid supply-holes extending from said chamber, one to each of said sides.

4. A multiple electrostatic precipitating plant, a plurality of collectors therein, each constituted, by a cylindrical upright container tube, and a plurality of connecting elements holding said tubes together closely stacked in banks, each said element having a chamber for liquid therein, the said elements fitting together in theform of ferrules around the top of each said tube, each ferrule having swirl ports opening substantially tangentially into its interior and communicating with a plurality of said chambers.

5. A precipitating plant according to claim 4. wherein said tubes are stacked substantially in tangential contact and each of said ferrules is surrounded by six of said chambers and pierced by six of said swirl ports, each of the latter chambers.

6. A precipitating plant according to claim 5 wherein said ferrule-forming chambered elements fit together to form a complete header for all said tubes.

'7. A multiple electrostatic precipitating plant comprising a plurality of collectors, each constituted by an upright cylindrical container tube and a chambered ferrule at the top end of each said container tube pierced by at least one liquid supply hole from a chamber in the ferrule into the interior of the ferrule substantially tangentially to the inside surface of the ferrule, wherein each said ferrule is made up of a plurality of separate elements fitting together around a tube and at least one of said elements of each ferrule, by being formed as a part of two of said ferrules, engages and holds together at least two adjacent container tubes.

DEREK ROY WHITIET.

References Cited in the file of this patent UNITED STATES PATENTS Number 

